Does anyone in Glasgow know where I can get fluorescent light diffusers ? I don't need the whole fitting. I dropped the blasted thing as I was cleaning the diffuser & it broke. B&Q only has the complete unit.

Does anyone in Glasgow know where I can get fluorescent light diffusers ? I don't need the whole fitting. I dropped the blasted thing as I was cleaning the diffuser & it broke. B&Q only has the complete unit.